Process for recording sound.



R. L GIBSONJ PROCESS FOR RECORDING soum).

APPLICATION FILED DEC-29. I913- Patented June 5,1917.

3 SHEETSSHEET I.

Mir

IEI iLII I E N WITNESSES 2 IN VEN TOR.

R. L. GIBSON.

PROCESS FOR RECORDING SOUND.

APPLICATION FILED DEC.29| 1913.

Patented June 5, 1917.

3 S'HEETS-SHEET 2.

R. L. GIBSON.

PROCESS FOR RECORDING SOUND. APPLICATION FILED DEC. 29. I913.

Patented June 5, 1917.

3 SHEETS-SHEET 3- jg? I WITNESSES- INV'E-NTOR.

A TTORNE Y ROBEiRi'll L. GESON, 0F PHILADELPHIA, PENNSYLVANIA.

Process FOR nncoanme scum).

Specification of Letters Patent.

Patented June 5, 1917.

Application filed December 29, 1913. Serial No. 809,187.

I To all whom it may concern:

Be it known that I, ROBERT L. GIBSON, a citizen of the United States, and resident of the city and county of Philadelphia and -State of Pennsylvania, have invented an Improvement in Processes for Recording Sound, of which the following is a specification. I

Heretofore, in the manufacture of gramophone records, namely, those of disk form having a spiral groove in their face for operating a stylus of the sound box, two general methods of manufacture have been employed. The first of these relied upon the etching process, and consisted essentially of floating upon the surface of a polished disk of zinc a thin greasy or waxy coating, such as may be produced by a wax dissolved in gasolene or other solvent, and after subjecting the surface so produced to the stylus of a recording machine vibrated in accordance with sound waves whereby the spiral tracing so formed will expose the zinc, etching the exposed surface to form a spiral groove having lateral undulations which correspond to the tracing of the stylus. The etched disk so produced is then cleaned and subjected to an electroplating operation, such as employed in electrotyping, and an inverse matrix is produced which, after being backed to strengthen it, may be. subsequently employed as a die from which to impress in hard rubber or equivalent compounds a record groove which may be used in the reproducing machine, such as the ordinary gramophone. In this manner, duplicates from the master record may be employed in reproducing the sound waves. Great objection, however, has always resulted from the fact that in any etching process,

the lateral walls are under-cut owing to the,

fact that the acid eats laterally as well as vertically, and consequently the records produced under this process have not been considered satisfactory, and the process has been superseded. The second process, and which 'is that commonly. employed at the present time, comprises the following steps: A disk is coated with a waxy compound, such as metallic soap, capable of being engraved, and after being carefully smoothed and leveled, the stylus of the recorder acting as an engraving tool is caused,'through the rotation of the disk, to engrave a spiral groove thereirrof even depth and with lateral undulating side walls. This engraved disk is then dusted with plumbago and subjected to an electroplating process by which a matrix is produced having a raised spiral upon its surface, the said master matrix, after being hacked and strengthened,

is in a form capable of being used as a die.

for reproducing in suitable earthy com, pounds resembling hard rubber, duplicate records suitable for use in connection with the reproducing machine, such as the ordinary gramophone. Ordinarily, this master matrix is copper, secured by the electroplating process, is not employed as the die because it would soon wear out, and as there In the first process above mentioned, in Y which etching was employed, it has also been customary to dub the matrix as desirable results would not be secured by attempting to use the zinc disk afteretching more than in the first instance. In such case, the copper matrix produced from the zinc was emloyed to. produceduplicatedies by dubing operations in which the die was impressed in wax surfaces which were subsequently electroplated, thereby multiplying the defects. V y In no case in these prior methods has the copper matrix, produced from the engraved or etched disk, been capable of use with a gramophone instrument as they did not have embodied in their construction a groove to receive the stylus. Moreover, the dubbing operations, which have universally been employed, introduced undesirable defects and multiplies existing defects which may have 'been inherent in the original matrix, into the commercial records which are produced from the dubbed dies, and this is important because the very slightest irregularity in the grooves will produce marked defects in the reproduction of sound, as is well known to those skilled: in the art.

The object of my invention is, to provide a new method of producing an original sound record or phonogram from which it will be possible to reproduce more nearly perfect commercial records than it has heretofore been possible to manufacture. Generally speaking, the present invention consists in.

building upon a polished surface of a rotating disk a continuous raised ridge or rib having lateral undulations corresponding to sound waves, which may be used as a mold (directly or indirectly) to form in a plate or disk of suitable material a complementary a ing diaphragm of a recording machine, and

which, upon emergence from the stylus, is

deposited upon the surface of a revolving plate and there immediately congeals or solidifies to form the rib or ridge above mentioned.

In order that the phonautographic ridges shall be formed free from defects that will prevent the accurate recording and reproduction of sound, including the harmonics and overtones, several factors are important.

First, the thread or stream of plastic ma terial should be of substantially less crosssection than the phonautographic ridge formed thereby and the stylus orifice should therefore be exceedingly fine, that is, much finer than the finest orifice through which the material could pass by gravity or by the drawing effect produced by the deposition of the ridge. Second, the material of which the phonautographic ridge is formed shall be one which, by the use of heat, may be maintained fluid until after it emerges from the stylus and will quickly harden upon striking the traveling surface which receives the record. Third, the material shall be subjected to considerable pressure in order to force the same through the stylus orifice. Fourth, the speed of ejection of the material shall be substantially greater than that at which the receiving surface of the revolving plate moves.

It must be appreciated that the factors of size of orifice, pressure, temperature and relation between the speed of ejection of the material and the rate of travel of the receiving plate, arenot constant but are variable, more or less, relatively to each other. For example, it is obvious that the smaller the orifice, the higher the pressure required to eject the material and the greater, therefore, the velocity of the minute stream dis-- charged from the stylus relatively to the speed of travel of the moving surface.

do so, would convey no particularly useful information. An explanation of the method of forming the stylus will, however, enable those skilled in the art to carry out the process. It is well known that if a glass tube be heated and then drawn out, the internal I and external diameters of the tubes willbe reduced proportionately. I take' such a glass tube, heat the lower end, and draw it to an exceedingly fine point, which is broken off to expose themicroscopic orifice. By drawing, a glass tube to an exceedingly fine point as described, the orifice may be much smaller than that of a capillary tube and the stream ejected will be much smaller than the completed ridge.

The material which is forced through the hollow stylus upon the rotating plate is of such consistency and character that, while it will flow at the high temperature and pressure which are maintained, it will immediately solidify and congeal upon the plate. to form a raised rib having the lateral undulations imparted by the vibrations of the stylus. Substances that I have found efficient are beeswax or beeswax and parafiin.

The pressure required to eject the material from the stylus with the speed required cannot be defined within very narrow limits, for the obvious reason that it will vary with the character of the material used, the size of the stylus orifice, the temperature and other conditions. Thus, while the orifice in the stylus will be exceedingly minute, when producedin the manner described, it is obvious that there is no way by which the microscopic diameter of the orifice, which cannot be measured, may be accurately predetermined; nor is it at. all important that it should be accurately predetermined. But it is clear that the smaller the material. must be forced throughit in order to build up a soundridge of the desired dimensions. He e, at once, arises the necessity orifice the greater the speed with which the to be understood that I do not mean to limit myself to the use of any precise pressure, provided it is sulficient to eject the material employed in a fine stream through the stylus point to produce the phonautographic ridge.

Necessarily, with each stylus made, different pressures must be tested to determine what pressure will suflice to properly force the material through the stylus. After the proper pressure is determined, that pressure may be regularly employed as long as'the stylus is in use. The stylus-will last indefinitely, in the absence of accident.

The temperature required to maintain the material in a liquefied condition will, of course, vary with the material employed. Whether it is beeswax, or beeswax and par aflin, or some other suitable substance, the temperature required to maintain it liquid is well known in the art and need not be specified. Of course, means should. be provided to maintain in a heated condition the stylus and the passageways through which the material passes to prevent it cooling or congealing before it reaches the plate, and a different degree of heat may beimparted to the stylus point. It is also obvious that the temperature may exceed the minimum re quired and that the higher the temperature the more free the flow, and that the higher the temperature the lower will be the pressure required to insure the proper flow. It

will therefore be clearly understood why the temperature and pressure are variable factors which must correlate not only with each other, but, with the necessarily variable, and not accurately predeterminable,

factor of the size of stylus orifice. Any oneskilled in. the art can readily regulate the factors of temperature and pressure to suit the particular stylus employed. No more definite information can be furnished, because no moredefinite knowledge is possess'ed by me, notwithstanding which I have had no difiiculty in successively carrying out the process on an extended scale.

Another important factor in the process is the ejection of the material in less section and volume than is required. forthe completed ridge, the ridge being formed by a building up of the material upon itself. This is accomplished by the ejection of the fine stream of material-from the stylus. at a -velocity substantially greater than the speed of rotation of the plate on which it is deposited. A very fine stream of materlal will solidify, congeal or set very quickly,

and there is little or no tendency of thestream to spread upon the plate. So far as this feature of the invention is concerned, it is a matter of indifference what the absolute speed of rotation of the plate may be or whatmay be the absolute section or velocity of the stream emerging from the stylus. Practical commercial considerations,

however, imperatively dictate the usual speed of travel of the receiving 'disk, say about eighty revolutions per minute. There is, in any event, no occasion to depart from the customary speeds employed to record and reproduce sound.

While, heretofore, it has been proposed, as a first ste in the manufacture of sound records, to eject a liquid stream upon a rotating plate, such stream, while of course quite small, was never successfully made fine enough to favorably compare either mechanically or phonetically with the hairlike grooves in the common forms of talking machine records, and, furthermore, said stream, being relatively slow in congealing has always had a tendency to spread or flow after being deposited upon the plate, thus losing the characteristic shape of the indi vidual waves of which it is composed. And again, being coarse and deposited on a surface moving at the same rate of speed as the rate of deposition, that part just ejected from the stylus whileat one extreme in its vibratory path, is easily drawn away from its intended position by said stylus as the latter moves to its other extreme position. In other words, the permanent ridge formed of the deposited material does not delicately and minutely conform to the vibrations of the stylus while depositing the same.

In the present invention, however, the ridge of waxy material or its equivalent deposited by the vibrating stylus upon the rotating plateis of spiral form and is in itself a complete and accurate phonautogram, complementary in form and dimensions to the spiral undulatory groove in a sound disk or record used for the reproduction of sound. The record thus produced may be used as a mold for the production of a master by electro-deposition, or in any other manner. In my Patent No. 943,631, dated. December 14, 1909, there is described a method by which commercial records may be produced from a mold of this general character by electroplating.

According to this method the mold is coated with plumbago and is then plated with copper. The plating thus produced is stripped ofi carryingwith it, to a large extent, the waxy material which forms the raised ridge. The stripping thus produced is cleaned to remove all traces of the waxy material and is then electroplated to pro-' duce a die or matrix having a raised ridge identical with that formed by the waxy material deposited originally on the plate.

ited on the surface of the revolving plate,

and that other methods than that described may be used for the purpose. If the material composing the ridge has sufiicient so that the ridge, by reason of the compara:

strength and rigidity it may be used di- In my present process the raised phonau-' tographic ridge is preferably not deposited to its full dimensions at once by the ejection of a proportional quantity of the material forming the ridge from the stylus, but by the gradual deposition of the material in volume less than that of the finished ridge,

tively retarded rotation of the plate in relation to the'velocity of ejection of the material, is built up upon itself to the required size. The great advantage of this method of producing the phonautographic ridge is that the exceedingly small stream of mate rial ejected from the stylus will congeal muchmore rapidly and retain the undulations imparted by the vibrations of the stylus more perfectly than would be possible with a larger stream, or with a stream of the full size of the line being laid.

Any suitable apparatus may be used for carrying out my process. In the drawings I have shown an apparatus, especially adapted for the purpose, which forms the subject matter of my application 809,188, filed December 29, 1913, and also a stylus, especially adapted for ejecting the exceedingly fine stream of material, which forms the subject matter of my application 809,186, filed December 29, 1913.

Figure 1 is a vertical sectional view of the sound recording apparatus. Fig. 2 is a transverse vertical sectional view of part of the same showing the recording stylus and its supporting frame at right angles. to the position shown in Fig. 1; Fig. 3 is a horizontal section on the line AA of Fig. 1; Fig. 4 is a perspective yiew of the frame or head which carries the recording stylus; Fig. 5 is a vertical sectional view on an enlarged scale of the recording stylus and the thimble which carries it; Fig. 6 is a view of the stylus and its inclosing casing showing a modification of the means for supporting the stylus against transverse vibration; Fig. 7 is a plan view of a sound-record produced by the apparatus shown; and Fig. 8 is a transverse vertical section of part of the same on an enlarged scale.

A hollow vibratory stylus a is operated by the impulses transmitted to it by the vibrations imparted by sound waves to the dia phragm of a recording instrument I). This stylus communicates with a reservoir 0 containing the material which forms the raised rib constituting the phonogram whichis de posited on the rotating disk or plate (l. The material in a melted state is forced at very high pressure from the reservoir through the stylus upon the surface of the rotating plate 01 and forms thereon a spiral line having lateral undulations corresponding with the vibrations imparted to the stylus by the sound waves.

To produce the spiral line the plate (1 is rotated by a suitable motor (2' and is simul-v taneously moved radially by a feed screw 03 in the manner well known in the production of disk sound records.

The solidified or congealed material when thus deposited forms upon the surface of the plate d a raised undulatory spiral rib a The rib thus formed ordinarily assumes a .more or less semi-elliptical final shape as shown in Fig. 8. Y I

The stylus a may be made of any material which can be provided with a sufliciently small orifice to deposit a stream of the necessary fineness ,to produce the phonautographic ridge. I prefer to form the stylus from a glass tube having its lower end a drawn to a point, as hereinbefore described. The reduced thread-like end of the tube thus produced is connected with the diaphragm of the sound box 6 by a filament b of glass or other material, and possesses such resiliency that it will readily respond to the vi.- brations of the diaphragm. The shank a of the glass tube may be left of normal size while the upper portion a is preferably. en-

larged into a bulb, which is filled with cotwith the main-frame g, which carries the reservoir,.by a detachable frame or head f,

and this head also carries the recording sound-box b.

As shown, the detachable head? is a plate attached to the main-frame g by screws 9 and having a spherical head it adapted to fit a complementary socket h in a portion 9 of the frame 9. The plate 7 is provided on the under side with a threaded nipple 2', to which the stylus is attached by a thimble 'i' and nut '5 The enlarged or bulbous upper end a of the stylus is contained within the thimble c" and the shank a extends through an open- I ing 2' in the bottom of the thimble. Owing to the great delicacy of the stylus it is important that it should not come into direct contact with the metal of the thimble. The opening 1' through which the shank projects is therefore made slightly larger than the shank and the latter extends through a lead ferrule j and asbestos washers 5" in the bottom of the thimble which act to support the shank of the stylus but prevent contact with the metal walls of the thimble.

The stylus isintroducedthrough the open top of the thimble and is held in place by a spring 70. As shown the spring is interposed between a plug it screwed into the open end of the thimble and a cap k acting upon the top of the stylus and holding it in place. A washer or washers k of felt or other porous material may be interposed between the cap is? and the stylus. The plug and cap is and k are provided with passages lc* and I0 respectively, through which the melted material, which forms the phonautographic ridge, is forced from reservoir into an through the stylus.

While my invention is not concerned with the manner of forming and applying the stylus, I consider the following a simple and convenient manner of forming a stylus suitable for carrying out my process: The glass tube is first blown to produce the bulbous end a after the tube is filled with the cotton or filtering material 6' it is introduced in the thimble i with the shank projecting through the ferrule j and washers j. The spring k with the plug cap 70 and the washers It are then applied and the plug k is screwed down to fasten the glass tube securely in place. v The lower end of the tube is then heated and drawn to form the fine point a. As the pressure at the top is applied through the cap 70 and the felt washers is", and the contact of the shank at the swelling of the bulbous end is with the soft lead ferrule j, the glass tube may be firmly secured without fracture, and when it is thus secured the lower end a may be drawn in the manner described to anexceedingly fine point.

The stylus and the thimblec" which carries it are connected with the nipple i by the nut 5 with the passageways 10*, k in communication with a passage 72, extending through the thimble and boss of the frame I and communicating with a passage m leading through the frame 9 to the reservoir 0. This passage is controlled by a needle valve n. I

The reservoir 0 which contains the wax or material of which the ridge is formed preferably consists of an elongated capsule having walls of lead or other flem'ble material. This is connected by a tubular nut c with the frame 9' and is inclosed in a chamber 0 containing oil, which latter chamber is in turn inclosed in a heating chamber p. The

reservoir 0 communicates through the hollow nut c with the passage m, and between the nut c and passage m is a. chamber h containing cotton or other straining material.

The chamber 0 communicates by a passage o' with a pump (not shown) by which the oil contained in the r may be put under very-high pressure. This pressure acting on the flexible walls of the reservoir c compresses them and forces the li efied e nut from which it is ejected upon the surface of the rotating plate d. In order that the wax or other material may be forced through the of the reservoir 0.

Any suitable means may be employed to maintain the material in a liquefied condition until it is deposited upon the plate (1. I have shown a heating chamber surround-- ing the oil chamber 0 into which hot air or steam may be introduced through passages p, p? from a pipe p". The chamber p may be provided with a relief valve 17*. The chamber p forms a heating jacket about the pressure chamber 0 from which snificient heat is transmitted to liquefy the wax or material in the reservoir 0.

To keep, in a heated condition, the stylus and passageways through which the wax or material forming the ridge passes, I inclose the stylus and connections in a casing to which heat may be applied. This casing is preferably made in two parts a, s, the upper part 8 inclosing the nipple i and the'connec- .tions of the stylus with it, while the lower part s incloses the stylus. These two compartments are separated by a partition 8 and may be heated independently of one another, as by separate pipes t, t leading from the heating pipe 12 Thus a different degree of heat may be apphed the pomt of the stylus than is applied to its connection with the head f.

As the stylus is extremely delicate and responsive to the impulses imparted to 1t, it is of importance that it should be braced against lateral or transverse vibration, z. e. in a direction transverse that imparted by the sound waves. For this purpose I pre-- fer to einploy an angular strut or brace u extending from the sham]; a? to the pomt a and arranged at substantially a rightangle to the filament b by which the sound waves are transmittedfrom the soundbox 6 Thus strut or brace may be made of glass In Fig. 6 I have shown a modification m which 'the point of the stylus is connected with a wire or filament 21, extending hansversely through the casing s at right angles to the The particularmanner in wh ch the sound-box is supported and connected w th the hollow stylus is not ementlal to the mvention. I prefer, however, when the detachable frame or head f is used to connect the sound-box with it. To this end have shown the frame extended at one s de f and provided with lugs f which is carried a transverse pin to carrying a clamping to which embraces the sound-box 6. far as concerns any sub ect-matter herein set forth which is also set forth in my prior application, Serial No. 379,712, filed June 14, 1907, this application is a continuation thereof.

What I claim is 1. The method of forming a record of sound Waves Which consists in depositing upon a relatively moving surface a stream of fluid which r'eadily solidifies and laterally vibrating said stream immediately before it strikes said surface to form thereona' ridge having therein lateral undulations corresponding to sound Waves.

2. The method of producing a record of sound which consists in depositing upon a relatively moving surface, by a recording member, vibrated by sound Waves and maintained out of contact with said surface, an undulatory ridge of approximately uniform width corresponding to sound vibrations.

3. The method of recording a sound Which consists in projecting upon a relatively moving surface a stream of fluid adapted to readily-congeal and form on said surface a ridge and causing sound impulses to vibrate said stream as it approaches said surface to cause said ridge to assume an undulatory form presenting a sound record in distinct relief.

4. The process of forming a permanent sound record Which consists in forming an original record by depositing upon asuitable relatively moving surface a substance adapted to maintain itself in a ridge, said ridge having lateral undulations corresponding to sound Waves, and forming a permanent record from said original record.

5. The process of recordin sound which consistsin depositing, While uid, a readily congealable substance upon a relatively moving surface, at a velocity substantially exceeding the rate of movement of said surface' 6. The process of recording sound which consists in projecting a stream of fluid upon a relatively moving surface at a velocity substantially greater than the speed of travel of said surface, and causing sound impulses to vibrate said stream.

7. The process of recording sound Which consists in projecting upon a moving surface a fluid stream of material adapted to readily congeal and of a section substantially less than. that of the deposited phonautographic Wave, causing'sound impulses to vibrate said stream as it approaches said surface, and imparting to said stream as it approaches said surface a velocity substantially exceeding the speed of travelof said surface, therebycreating a built-up record in distinct relief of said sound impulses.

In testimony of Which invention, I hereunto set *my hand.

ROBERT GIBSON.

Witnesses: v

R. M. KELLY, Mrs. H. MAUD WHITE. 

